The role of epidural steroid injection (ESI) in spinal stenosis (SpS) has been controversial, with no Level 1 or Level 2 evidence clearly demonstrating effectiveness in this population. Despite the lack of evidence for this procedure, it is generally viewed as first line treatment for SpS, especially for patients who prefer to avoid surgery. Most studies of ESI have included mixed populations (i.e. disk herniation, stenosis, degenerative spondylolisthesis) and frequently have compared steroid to a local anesthetic or saline control, a potential problem as the local anesthetic or saline could have a therapeutic benefit. The Spine Patient Outcomes Research Trial (SPORT) provides a large observational database with which subgroup analyses can be performed. Dr. Radcliff and his colleagues from Thomas Jefferson University and Dartmouth performed such an analysis, comparing surgical and non-operative outcomes between patients who received an ESI within 3 months of enrollment in SPORT and those who had never received ESI. Patients who received an ESI prior to enrollment or after 3 months from enrollment were excluded in order create a more homogenous ESI population. Over the four years of follow-up, they found significantly worse surgical and non-operative outcomes in the ESI patients on some outcome measures (primarily the SF-36 physical function and bodily pain scales), while there were no significant differences on the Oswestry Disability Index (ODI) or the Sciatica Bothersomeness Index. Epidural steroid injection did not clearly reduce surgery rates, with increased crossover to surgery among ESI patients who initially chose or were assigned to non-operative treatment and increased crossover to non-operative treatment among ESI patients who initially chose or were assigned to surgery. Somewhat surprisingly, ESI patients had significantly longer surgery times and length of hospital stays after surgery. Additionally, ESI patients had surgery complicated by dural tear at over twice the rate compared to non-ESI patients (15% vs. 7%), though this difference was not significant (p=0.21).
Based on the results, the authors suggest that ESI is associated with worse surgical and non-operative results for SpS patients. While this was true on some outcome measures, other measures—such as the ODI—did not show any significant differences. This study was not an RCT comparing outcomes between patients randomized to ESI and no ESI, so the results could be affected by unmeasured confounders. In other words, there could be factors associated with choosing an ESI that are responsible for the worse outcomes rather than the ESI itself. As such, these data may not convincingly demonstrate that ESI causes worse outcomes, however, there is no suggestion that ESI was beneficial in this population. One concerning finding was that patients who had underwent ESI had significantly longer OR times and lengths of stay. Additionally, the durotomy rate was twice as high in the ESI group, though this difference was not significant due to the small numbers involved. While there may have been some confounding by the ESI patients undergoing fusion at a slightly higher rate (15% vs. 10%), these operative factors suggest that ESI could create adhesions or have other effects that make surgery more difficult. While this study is not going to mean the end of ESI for SpS patients, it adds to a flawed but extensive literature suggesting that ESI is not very effective for this condition. There is very little evidence that any non-operative treatment is effective for SpS, so ESI will likely remain in our armamentarium as an option for patients who wish to avoid surgery or who have medical comorbidities that make surgery risky. This study does provide us with good data to share with our SpS patients who are considering their treatment options, and they should be informed that ESI is generally not helpful in the long-term.
Please read Dr. Radcliff’s article on this topic in the February 15 issue. Will this article change how you use ESI in the SpS population? Let us know by posting a comment on The Spine Blog.
Adam Pearson, MD, MS
Associate Web Editor